1. Field of the Invention
The present invention relates generally to tow dolly designs secured to a rear hitch associated with a tow vehicle (typically truck, camper/RV or the like). In particular, the present invention discloses an articulated tow dolly, capable of being converted from a normal use position to a retracted or “fold up” position, and by which the tow dolly wheels are elevated off of the ground and the assembly supported in elevated fashion by the vertical load carrying capability of the heavy-duty hitch assembly.
2. Description of the Prior Art
The prior art is well documented with examples of tow dolly and related trailer designs. The objective in many instances is to facilitate the storage of the dolly or trailer when not in use when being towed behind a vehicle.
A first example of a tow dolly design selected from the prior art is set forth in U.S. Pat. No. 5,342,162, issued to Robinette, and which teaches a tow dolly having both ramp loading and tilt loading capability. The dolly includes a vertical pivot bolt to allow the towed vehicle to be more easily maneuvered around turns. Additionally, the dolly has the capability to be folded to stand on its ramps, and thus assume a substantially upright configuration for storage.
U.S. Pat. No. 6,164,897, issued to Edwards, teaches another tow dolly design having ramps for receiving wheels of the vehicle being towed, the ramps being adjustably mounted such that vehicles of different wheel spacing between the front and/or rear wheels may be accommodated. The wheel assemblies are also adjustably mounted to accommodate either a narrow width vehicle or a wide width vehicle. Additionally, multiple bores are provided in the main frame to accommodate the two mounting positions of the wheel ramps to accommodate the mounting of the axle assemblies in the two positions.
Referring further to Hull, U.S. Pat. No. 5,727,920, a vertical lift towing dolly is disclosed and which includes variable, attachable platforms, each being individually designed for a specific purpose, e.g. hauling a boat, car, motorcycle and the like. A hydraulic cable system facilitates the vertical lift of the entire frame. Further, the design facilitates selective variation of the distance between the wheels, a towing tongue removably affixed to the axle, an arrangement to accept variable sized trailer hitches, to vary the height of the trailer, and to permit trailer disassembly for transport and storage.
U.S. Pat. No. 6,767,025, issued to Hagen, teaches a folding trailer for off-ground storage on a towing vehicle. A rectangular frame is mounted on a pair of wheels and a “T” shaped member. Hinged to a transverse cross brace which generally bisects the rectangular frame are two arms which terminate proximate to distal ends of the “T” shaped member. In the unfolded position, the leg of the “T’ shaped member extends in front of the wheeled frame so as to define a tongue. When folded, the tongue extends generally perpendicularly to the wheeled frame and can be inserted directly into the hitch receiver, held there-within by a pin, and in order to allow the two wheels to ride free above the ground.
U.S. Pat. No. 6,623,028, issued to Johnston, teaches a stowable trailer/dolly system capable of being lifted from the ground and in order to be located beneath, or nest within, the chassis or sub-frame of a vehicle. When in use, the trailer/dolly is either coupled under a vehicle or trailer as a dolly only or is lowered and moved rearwardly of the vehicle so it can be towed behind the vehicle using the hitch. The chassis of the trailer/dolly is in the form of a rectangular frame which can be enlarged in size by telescopic movements of associated support members. Additional small wheels are provided on a sprung stub-axle.
U.S. Pat. No. 6,179,368, issued to Karlsson, teaches a modular fold-out camping unit designed to be carried largely by a vehicle's hitch receiver for transportation while independently supported to the ground with height adjustable legs while in use. A load-carrying base (or floor) plate is supported by a hitch arm. Additional floor boards may be provided and which are inter-attached to the floor plate by hinges to be unfolded to define an extended floor area whereupon an enclosure in the form of a semi-permanent tent structure is erected.
Finally, U.S. Pat. No. 3,877,714, issued to Black, teaches a trailer attachment for extending the effective length of a pickup truck box. A pair of eye bolts are secured to the floor of the pickup box adjacent to each side of the tailgate. The trailer includes a platform with apertures alignable with those associated with the eye bolts which are attached by removable pivots. The rear end of the platform has a castor wheel secured thereto to support its outer end and provide maneuverability thereto. The platform is fixed relative to the cargo box floor and to the extending portions of the elements which rest thereon.